def PrimeList(N):
    P = [1] * (N + 1)
    P[0] = P[1] = 0
    for i in range(2, N + 1):
        if P[i]:
            for j in range(i + i, N + 1, i):
                P[j] = 0
    PL = []
    for i in range(N + 1):
        if P[i] == 1:
            PL.append(i)
    return PL


M = int(input())
N = int(input())
C = list(map(int, input().split()))
PL = PrimeList(M)
PLS = set(PL)

dp = [-1] * (M + 1)
dp[M] = 0
for c in C:
    for i in reversed(range(c, M + 1)):
        if dp[i] != -1:
            dp[i - c] = max(dp[i - c], dp[i] + 1)
maxv = max(dp)
ans = maxv
for i in range(M + 1):
    if i in PLS and dp[i] != -1:
        ans += dp[i]
print(ans)